Technical Abstract:
Water quality and public health impacts of animal manure produced at large concentrated animal facilities prompted the need for viable solutions for their conversion and reuse. Our laboratory at the Southern Regional Research Center, as part of the Agricultural Research Service of the U.S. Department of Agriculture, has shown that it is feasible to convert animal manure into chars and granular activated carbons used for heavy metals remediation. Pyrolytic products or chars are low porosity, lower surface area materials that are intermediate products in the development of activated carbons. Toxic metals contamination of various water sources is a significant problem in many parts of the United States. Neither chars nor activated carbons, which can be produced from a number of precursor materials including coal, wood and agricultural plant wastes, have been examined for remediation of this problem. Chars are produced by pyrolyzing a pelletized sample of animal manure (sourced from poultry, dairy cow and swine) under inert atmosphere. High porosity activated carbons are produced by steam activating chars with surface areas as high as 550 m2/g. Both chars and activated carbons have been characterized for their physical properties and most importantly their ability to adsorb metal ions. These properties vary depending on the source of the manure, and in general it has been determined that poultry manure-based carbons (broiler and turkey) far exceed all other carbons (sourced from coal, wood, coconut shells) in their ability to remove heavy metals from solution. More recently promissing results have been obtained when the manure-based carbons were tested for their ability to remove trihalomethanes from solution. A holistic approach is fundamental when producing value added products such as animal manure-based carbons in order to realize maximum return. In this particular situation, in addition to bio-char and bio-carbon, two other streams are produced in the process. These are product gas or syn-gas and bio-oil and they will be characterized for their potential use in the near future. Meanwhile, a preliminary feasibility analysis gives an estimated cost of production for the value added carbons from the manure. The conversion of readily available and renewable animal manures into chars for wastewater remediation might be an alternative to a serious disposal problem and at the same time create new markets for animal manures and new opportunities for animal farmers.